Cleaning Roof Shingles

From New to Dirty & Dirty to Clean

We all know the feeling of owning something brand new. Whatever it is whether it be a car, a new pair of shoes, clothes, or a new roof it feels nice, new and clean. On the other hand we all also understand that new things don't stay new forever.

Roofs are exactly the same. The day the roof was finished it looked so pristine, clean and new. Years later the roof may start looking older and may even need cleaning. This page has been created to aid those who are thinking about cleaning roof shingles by themselves or through a professional roof shingle cleaning company.

*We recently wrote an article on how to clean vinyl siding. Hopefully it will help you if you need to clean your vinyl siding.

New Article: Do Gutter Guards Work?

What Causes Roof Shingles To Get Dirty: How To Clean Them

There are many things that cause roof shingles to get dirty and unsightly. Here we are going to focus on the main causes of dirty shingles.

• This guide is good for cleaning architectural shingles and 3-tab shingles.

Falling Debris

Falling debris from trees is probably the number one cause of dirty roof shingles. Some of the most common types of debris that ends up on roofs are leafs, sticks and branches, pine straw, and acorns. Some of the debris falls on the roof, some of it is blown on the roofs, and other debris is brought there by animals such as birds and squirrels.

Negative Consequences of Debris on Roof Tops

• Debris looks bad on the roof. — Most everyone cares that their homes look good and a dirty roof obviously does not look very kept up or nice.
• Debris can cause roof damage and roof leaks. — Some people wonder how a bunch of leafs and sticks can damage a roof. The answer to this inquiry is that the leafs, sticks, and debris can create a dam that blocks rainfall from leaving the roof top. When this happens a buildup of water sits and can backup underneath the shingles. This will cause leaks, rotting in the roof decking and can even leak inside the interior of the home causing water damage in walls, sheetrock, floors, and so forth. It is very important to make sure that roofs are regularly cleaned by removing debris.

Best Ways To Clean Debris Off of Roofs

• By Hand — Debris is often light and doesn’t require heavy equipment to remove it. One of the easiest ways to remove debris from off of a room is with your hands. This may require you to get onto your roof. Remember to always be aware of proper roof safety procedures because you can fall off of a roof and seriously injure yourself and or die.
• With a blower — Another easy way to remove leafs, sticks, and other debris from the roof is with a blower. If you have access to an air blower, then feel free to use it to blow off the debris. For many, this is a preferred method because it doesn’t require much bending over or getting dirty.
• A soft broom or brush — Remember that when using a broom or brush on your roof that you don’t want to apply too much pressure. Too much pressure can remove roof granules which will reduce the life of the roof.

Algae or Black Stains

Many people are very aware of the black stains that often appear on roof tops. People who are suffering from black stains often ask what the black stains are and wonder if it is damaging their roof. This “roof mold” is actually dead algae on the shingles. Black stains or this dead algae appears on the north side of roofs because it doesn’t get as much sun and thus remains more damp for a longer amount of time.

Can The Algae Harm The Roof

Not really. By that we mean that the algae simply feeds off of the limestone that is in the asphalt shingles but it doesn’t really damage the shingle. Black stains or a.k.a “Roof Mold” is more of a cosmetic problem.

*Tip: One way to prevent algae growth on roof tops is to get algae resistant shingles. This will only work when you are getting a roof replacement or a new roof installed on a brand new home.

How To Clean The Black Stains

In order to clean the black stains off of the roof you will need to apply the right cleaning solutions. There are many DIY solutions that people swear by. Some of these include bleach, hot water, soap, and other chemicals. Before applying any type of chemical or cleaning solution to the roof check with a professional, your shingle warranty, and test it on some spare shingles that you may have or you can buy. Remember you can always buy a bundle of shingles from a local home depote, lowes, or roofing supplier for around $28. It will be worth your investment to know that your algae roof cleaning solution is safe.

Check out some DIY roof cleaner recipes on one of our Roofpedia.com pages about cleaning moss off of roofs!

Don’t Do!

Do not take a pressure washer and try to pressure wash your black roof stains away. Pressure washing a roof is a big no no. In fact, if you pressure wash your roof you will most likely no longer qualify for your roofs warranty. Pressure washing roofs can blow off the granules that are there to protect the asphalt in the shingle from the UV rays of the sun. A lot of missing granules is a sign that it is time to replace your roof.

Moss

First off, we would like to point you to one of our more comprehensive articles about removing moss on roofs. The article goes into detail talking about what moss is, how to kill it, how to prevent it, and what negative consequences come as a result of it being on your shingle roof.

Many people think that moss looks neat on roof tops but regardless of how it looks it can seriously damage the roof and the structure of the building by allowing leaks through the shingle roof.

Warnings

This is a basic list of risks that you should be aware of when cleaning roof shingles yourself or are getting your roof cleaned. If you are an expert in this field and would like to add some risks that we have not included, please apply to become an expert for Roofpedia.com.

• You may fall off of your roof. Many people fall off of roofs while cleaning roof shingles.. Roofs are steep and can get extremely slick with water and cleaning solutions on them.
• If you use your own, none tested cleaning solution, you may ruin your shingles.
• Some roof cleaning solutions can damage plant life as it drains off of the roof.
• Do not use a pressure washer to clean your roof. Pressure washers are known to remove the granules on roofs which will dramatically reduce the life of your roof.
• Walking on your roof can loosen granules & tear shingles (depending on the age of your roof).
• Scrubbing shingles with a stiff brush or broom can cause shingles to tear or granules to be dislodged. Be careful if you decide to scrub. We don’t recommend scrubbing shingles in order to clean them.

Resources

FAQ article from a local roofing company in Baltimore, MD - MyRoofClean.com

An article talking about roof debris from an oregon roofing company - Roof Life in Oregon

Black streaks on a roof: why they spread and come back

Black streaks usually start high on a slope and run downhill in stripes, because rain carries the growth down the same paths the water takes. They appear first on the shadier faces of the house and are easiest to see on light gray, white or tan shingles, though dark roofs grow them too.

The algae travels on the wind as tiny spores, and birds and squirrels carry it from roof to roof. That is why one streaked house on a street is often followed by its neighbors, and why a new roof in a streaked neighborhood can start showing it within a few seasons. The limestone mixed into ordinary asphalt shingles gives it something to feed on.

Cleaning removes the streaks you can see but not the spores drifting over from next door, so the streaks come back. How fast depends on shade, humidity and how long the roof stays wet after rain or heavy dew. Cutting branches back, keeping the roof and gutters free of debris and adding metal strips near the ridge all slow the return. When the roof is finally replaced, algae resistant shingles are the longer answer.

Soft wash roof cleaning: what a professional visit looks like

A roof cleaner who soft washes starts on the ground. They soak the shrubs, flower beds and lawn under the drip line so the plants are full of clean water before any solution runs off the roof, and they cover delicate plants, patio furniture or a fish pond if needed. Downspouts may be turned away from gardens while the solution is on.

The solution itself is usually a diluted bleach mix with a surfactant that helps it cling, pumped through a hose at low pressure and sprayed from a ladder, from the roof, or from the ground with a long-reach nozzle. The asphalt shingle makers' trade association has long described this approach for algae: a chlorine bleach solution applied gently, left for a short while, then rinsed off with a gentle spray. It also says other chemicals should not be used without the shingle maker's approval.

Some cleaners rinse the roof afterward; others leave the solution to keep working and rinse only the walls, windows and plants. Ask which they do and why. By the end of the visit, the gutters should be flushed, the plants rinsed again, and the streaks gone or clearly fading. A cleaner who carries a pressure washer up the ladder for the shingles has brought the wrong tool.

Metal roof and tile roof cleaning

Metal roofs mostly need a rinse and a mild detergent. Painted metal panels carry a factory finish, and panel makers' care sheets generally warn against wire brushes, scouring pads, harsh solvents and strong pressure that can scratch or dull it. Mildew and algae can be treated with a diluted cleaner the panel maker approves, then rinsed well so nothing sits on the screws, seams or cut edges. Bare and coated metals react differently to strong cleaners, so read the maker's sheet before choosing one.

Wet metal is extremely slippery, and stepping in the wrong place on standing seam or corrugated panels can dent them. Most metal roof cleaning is done from a ladder or a lift with a long-handled soft brush or a low-pressure sprayer.

Clay and concrete tile roofs get the same low-pressure approach. Concrete tiles often have a colored surface coat that high pressure can strip away, leaving the roof blotchy, and both kinds of tile can crack under a careless step. Tile roofers place their feet on the part of each tile that overlaps the one below, where it is supported, and many owners leave tile cleaning to someone who works on tile all the time.

Roof cleaning cost and choosing a roof cleaning service

Roof cleaning is priced by the job, and the same few things move every quote: how big the roof is in squares, how steep it is, how many stories up it sits, and what it is made of. A walkable ranch roof with asphalt shingles is the simplest case. Steep pitches, three-story walls, tile or metal, and heavy growth all add time, equipment or both.

Extras change the number too. Ask whether cleaning the gutters, washing the streaks off the gutter faces, rinsing the walls and protecting the landscaping are included or added. Some companies offer a lower price for repeat treatments on a schedule, since a roof that is kept clean takes less work each time.

Before you hire, ask what solution they use and how strong it is, whether they rinse, how they protect the plants, whether they walk the roof, and whether they carry liability insurance and, where it applies, workers' compensation. Ask whether their method fits your shingle maker's cleaning guidance. Then compare written quotes for the same scope of work rather than simply taking the lowest number.

Questions people ask

What are the black streaks on my roof?

They are algae growth, most often a type that spreads by airborne spores and feeds on the limestone in asphalt shingles. The streaks follow the path rain takes down the roof and are mostly a looks problem. A gentle low-pressure cleaning removes them, and they return over time unless conditions change.

How much does roof cleaning cost?

There is no one price. Roof size in squares, pitch, height, roofing material and how heavy the growth is set most of it, and extras like gutter cleaning or protecting the landscaping add to it. Get written quotes from local roof cleaners that list exactly what is included.

Can you pressure wash a metal roof?

Most panel makers advise against high pressure because it can damage the painted finish and push water past fasteners and seams. A garden-hose rinse, a mild detergent and a soft brush handle most dirt; check the manufacturer's care sheet before using anything stronger.

Does Spray and Forget work on black roof streaks?

It is one of the no-rinse cleaners sold for roof stains. Its maker says to spray it on a dry roof and let rain finish the job, so black streaks fade gradually with each rainfall rather than rinsing off the same day. How fast depends on how heavy the staining is and how much rain falls.

How often should a roof be cleaned?

Only when growth or streaks appear. On a shady roof in a humid place that can mean every few years; on a sunny roof in a dry climate it may never be needed. Clearing debris and keeping trees trimmed between cleanings stretches the time.

This guide was updated in October 2026 with new sections and the questions people ask most.